As building materials, vehicle members, etc., those formed of a metal substrate such as aluminum are widely used. On the surface of such materials, a hard coat is frequently formed in order to impart abrasion resistance and rust resistance.
As examples of such a coating composition used therein, heat-curing types of coating compositions disclosed by Patent Documents 1 to 3 can be mentioned in general.
Patent Document 1: Japanese Unexamined Patent Publication No. 2002-265858.
Patent Document 2: Japanese Unexamined Patent Publication No. 2003-192980.
Patent Document 3: Japanese Unexamined Patent Publication No. 2003-292881.